(1) Field of the Invention
This invention relates to the land vehicles, and more particularly to guiding agricultural vehicles. It is submitted that a farmer is one having ordinary skill in this art. Therefore, this application is written so that a farmer would be able to make and use the invention.
(2) Description of the Related Art
The need to guide agricultural vehicles has long been recognized and many systems developed for it. An early system on a three wheel tractor configuration was to have a furrow follower pivoted to the axle carrying the front wheels of a tractor. The furrow follower was a pair of discs which were angled forward and downward so that they would naturally follow the furrow. If they stayed in the furrow, they were directly attached to the front wheels of the tractor so that the front wheels of the tractor would follow directly behind them.
Other systems or developements have included feeling fingers which would feel the stalks of growing crops. These fingers would be connected to electrical switches or hydraulic valves by which the tractor would be guided.
Normally the system would be connected to the tie rods of the front wheels or in some cases, to the hydraulic system of the tractor, which would be used with power steering.
In instances where irrigation pipes are mounted upon vehicles, the vehicles may be steered by a furrow follower as indicated above, or in some cases, a system would be used to follow an edge of a dike. In certain cases, the pipe carrying the water to the irrigation system was used as a guide wherein a follower ran along the pipe similar to the followers that ran in the furrows.
In other cases, particularly for irrigation systems, a wire was placed along the desired path. The wire might be above the ground which would have a feeler following the wire. Or in other cases, the wire was buried beneath the ground and followed by electronic sensing devices.
The prior art shows basically three units on a guidance system for agricultural vehicles. These are: (1) means on the vehicles for detecting the relationship of the vehicle and a path to follow, (2) analyzing means on the vehicle for determining steerage correction need as responsive to the means for detecting, and (3) means for steering the vehicle responsive to the analysis of the need responsive.
Basically, the mechanical detection means of the prior art were mounted about an upright or vertical axis, the same as the wheels of the vehicle to be steered. I.e., if the vehicle deviated from the desired path, the follower that followed the desired path would pivot about a vertical axis mounted upon the vehicle.